Super-junction Edge Termination for Compact Power Devices
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Solution Overview
Problem
Conventional semiconductor power device edge terminations occupy large areas, leading to inefficiencies as they take up a significant portion of the chip's area, especially in smaller devices, and are prone to electric field crowding and surface charge sensitivity, which complicates maintaining high breakdown voltages.
Innovation Solution
A super-junction structure with alternating P-columns and N-columns, creating a net P-type doping concentration to form a saddle junction, which distributes and spreads out electric fields, reducing crowding and increasing breakdown voltage without requiring extensive termination areas, achieved through varying column widths, dopant concentrations, and epitaxial layer designs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional edge termination structures (floating guard rings, electric field plates) are used to improve breakdown voltage, then breakdown voltage is improved, but termination area increases significantly
Solution Approach 1:
The termination region is segmented into alternating P-type and N-type doped columns (super-junction structure), creating multiple localized charge regions that collectively manage the electric field distribution across the termination area, allowing compact design while maintaining high breakdown voltage
Solution Approach 2:
Different doping types (P-type and N-type) are alternately distributed in the termination region to create localized charge regions with specific electrical properties, enabling precise control of electric field distribution in different areas of the termination structure
Solution Approach 3:
The super-junction structure employs asymmetric columnar doping patterns where P-type and N-type columns have different dimensions and doping concentrations, creating an asymmetric charge distribution that generates the desired saddle junction electric field profile for compact termination
2Area of stationary object
If termination area is reduced to increase active cell area, then active cell area increases, but breakdown voltage decreases due to field crowing
Solution Approach 1:
The termination region is divided into alternating P-type and N-type doped columns, creating multiple localized charge regions that collectively manage the electric field distribution, allowing compact design while maintaining high breakdown voltage
Solution Approach 2:
The doping concentration and column dimensions are precisely controlled to create a charge imbalance that generates a saddle junction electric field, fundamentally changing the electric field distribution pattern to achieve both compact size and high breakdown voltage
3Reliability
If conventional termination structures are used, then breakdown voltage can be maintained, but sensitivity to surface charges increases
Solution Approach 1:
Alternating P-type and N-type doped columns create localized charge regions with opposite polarities that counterbalance each other, reducing the net surface charge effect and making the termination less sensitive to external surface charges from passivation films and packaging materials
Solution Approach 2:
The asymmetric super-junction structure with charge imbalance creates a controlled saddle junction electric field that dominates over surface charge effects, reducing sensitivity to external electrical influences
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration significantly increases breakdown voltage while minimizing termination area, making the edge termination more compact and less sensitive to surface charges, thus optimizing semiconductor power device performance.
Implementation Method 1
Configuration and method to generate saddle junction electric field in edge termination
Implementation Method 2
A super-junction structure with alternating P-columns and N-columns, creating a net P-type doping concentration to form a saddle junction, which distributes and spreads out electric fields
Data Source
AI summary
This invention discloses a semiconductor power device disposed in a semiconductor substrate and having an active cell area and an edge termination area the edge termination area wherein the edge termination area comprises a superjunction structure having doped semiconductor columns of alternating conductivity types with a charge imbalance between the doped semiconductor columns to generate a saddle junction electric field in the edge termination.